Most HVAC systems that provide temperature control of architectural spaces (e.g., a room) include thermostatic controllers or thermostats mounted on the walls of the spaces for sensing and controlling the temperatures of the spaces. Such thermostatic controllers typically include an internal temperature sensitive element for sensing the temperature of the space, an input element for receiving an input designating a desired temperature, and a dial or digital display of the thermostat's operating conditions. Usually the temperature sensing element is housed in the thermostat but it may also be external to the housing and remotely located. A typical controller or thermostat also includes output elements such as relays, switches, or electronic drive circuits for sending control signals to the HVAC system.
Sometimes, the mechanical or digital display of the thermostatic controller is illuminated so that the display is more easily read. Although illuminating the display facilitates operation of the thermostat, the relatively small size of the thermostat dictates correspondingly small text in the display, which often requires users to stand very close to the thermostat in order to read the displayed information.
Prior approaches to make the information in the displays more easily readable have often been at the expense of aesthetics. Permanently illuminated displays are distracting and are generally totally utilitarian in appearance. Moreover, having a lighted display with numerals and/or text big enough to be easily viewed by those with impaired vision is generally neither practical nor aesthetically pleasing. For example, large numerals and/or text require a large display, which requires a large housing. Since a thermostat is typically mounted to a wall in a room, the large housing compromises the aesthetics of the room's decorations.